The present invention relates to a method for forming an image to display a background with being seen through an object.
As an art for displaying a background with being seen through an object, which is displayed on a game picture, an alpha-blending method and an additive blending method or the like have been known. Owing to the improvement of the processing capacity of a computer, even in a field of a personal game machine, the number of a type of a game machine provided with such an image processing function are increased. However, the details of such a type of a game machine are variously different in response to the capabilities, which are demanded for the game machine. Generally, while a manufacture mounts a high degree of an image processing function for forming a high quality image in a stationary game machine in competition with other rivals, there is a case that the image processing function is limited in a portable game machine with decreasing of a load of the image processing or the like in diagram. As an example of such limitation, in the case that a plurality of semitransparent objects are superposed, there may be a game machine such that a semitransparent object to be depicted at the headmost side is only blended with a background image at the furthest back with ignoring middle objects.
However, as described above, in the case of only blending the headmost semitransparent object as a background image, the depiction of the middle object is omitted, so that an unnatural image may be formed. For example, in a scene such that a semitransparent smoke is displayed at the headmost side as an object, that smoke is only blended with the background image, so that the depiction of the character or the like between the smoke and the background image is omitted and a character is erased from the game picture.
On the other hand, as a method, whereby an object can be seen through without blending images, there is known processing in which transparent areas and non-transparent areas are alternately arranged by one or some pixels in an object to be superposed at a front side so as to form a grid, and the background can be observed through the transparent areas. However, according to this method, the appearance of the transparent areas of the object is noticeably different from the appearance of the non-transparent areas of the object depending on the sizes of the transparent area and the non-transparent area, so that this involves a problem such that surface roughness is generated on the image.
An object of the present invention is to provide image forming method and apparatus, which are capable of displaying a semitransparent object without blending the object with a background and are capable of improving a quality of the image, and a program to be used in the method.
According to the first aspect of the present invention, there is provide an image forming method comprising the steps of: depicting a predetermined background; and depicting an object, in which a transparent area and a non-transparent area are alternately arranged in at least one direction, so as to superpose said object on the background, wherein, in the step of depicting an object, said transparent area and said non-transparent area are alternated between a plurality of frames in at least part of said object.
According to the present invention, while the background of the object is observed through the transparent area, the object itself is represented by the non-transparent area, so that it is possible to display the object in a semitransparent state. Since the transparent area and the non-transparent area are alternated between a plurality of frames, so that the difference of the appearances between the transparent area and the non-transparent area becomes inconspicuous in comparison with a case that respective areas are fixed. In other words, when the transparent area and the non-transparent area are fixed, respectively, the same portions of the front object and its background are seen, respectively, so that a user becomes aware of the difference of the appearances between the transparent area and the non-transparent area and the user is perceives this difference as roughness on the image. However, according to the present invention, by alternating the transparent areas and the non-transparent areas, the portions of the front object and its background to be seen are dynamically changed between the plural frames. As a result, it becomes difficult for the user to become aware of the difference of the appearances between the transparent area and the non-transparent area, so that the roughness on the screen is resolved. Particularly, in the case of displaying the object or the like on a display apparatus such as a liquid crystal monitor, of which reaction speed (a speed that the displayed content is changed) is relatively slow, the user never becomes aware of the difference between the transparent area from the non-transparent area by shortening an alternation period of the transparent area from the non-transparent area and further, the user gets the impression such that the object which is arranged at the front side is semitransparent in all portions.
The image forming method according to the present invention can be applied in the case that an object moves on the screen such as a game picture and also in the case that an object stands still on the screen. However, in the case that a position of the object is changed, there may be a case that the portion of the background to be seen is changed since the transparent area and the non-transparent area are moved. In such a case, if the transparent area and the non-transparent area are alternated, the portion to be seen is not changed. As a result, there may be a case that the effect of the present invention is counterbalanced. Accordingly, particularly, in the case that the object moves, it is preferable that the foregoing change of the position of the object between one frame and another frame subsequent thereto is detected and the alternation of the transparent area and the non-transparent area is controlled on the basis of that change.
According to the step of controlling alternation, it may be decided whether or not a predetermined area on a screen, which is identical with said transparent area in said one frame, is identical with said transparent area again in said another frame on an assumption that the alternation is not performed, and if identical, said alternation may be carried out in said another frame while said alternation may be postponed in said another frame if not identical. In this case, the area on the screen, which is identical with the transparent area in one frame, is identical with the non-transparent area in another frame and the area on the screen, which is identical with the non-transparent area in one frame, is identical with the transparent area in another frame, so that it is possible to bring about the effect of the present invention to the fullest extent.
Particularly, in the case that the foregoing transparent area and the foregoing non-transparent area are alternately arranged by one pixel in a lengthwise direction and a crosswise direction, a binary value obtained by adding coordinate values in the lengthwise direction and the crosswise direction, which define a position of said object on the screen, maybe calculated in said one frame and said another frame, respectively, in the step of controlling alternation, and then, if the lowest digit in respective added values are not changed, said alternation may be carried out in said another frame, while said alternation may be postponed in said another frame if the lowest digit in respective added values are changed. By performing suchlike processing, it is possible to easily decide whether a predetermined area on the screen is identical with the transparent area again or not in the case that it is assumed that the area on the screen, which is identical with the transparent area in one frame, is not alternated in another frame.
It is preferable that the foregoing one frame and the foregoing another frame are continuous to each other. As a result, it is decided whether or not the transparent area and the non-transparent area should be alternated for each frame, so that it is possible to form an image having the same quality as that of an image provided with the highly developed semitransparent processing by limiting the alternation period of the both areas as short as possible.
According to another aspect of the present invention, there is provided a program for forming an image, which is configured to make a computer perform the steps of: depicting a predetermined background; and depicting an object, in which a transparent area and a non-transparent area are alternately arranged in at least one direction, so as to superpose said object on the background, wherein, in the step of depicting an object, said transparent area and said non-transparent area are alternated between a plurality of frames in at least part of said object.
By executing this program with a computer, it is possible to realize the image forming method according to the present invention.
The program according to the present invention may include a following mode.
Said step of depicting an object further may include the steps of: detecting a change of a position of said object between one frame and another frame subsequent thereto; and controlling alternation of said transparent area and said non-transparent area on the basis of said change.
In the step of controlling alternation, it may be decided whether or not a predetermined area on a screen, which is identical with said transparent area in said one frame, is identical with said transparent area again in said another frame on an assumption that the alternation is not performed, and if identical, said alternation may be carried out in said another frame while said alternation may be postponed in said another frame if not identical. Said transparent area and said non-transparent area may be alternately arranged by one pixel in a lengthwise direction and a crosswise direction, and in the step of controlling alternation, a binary value obtained by adding coordinate values in the lengthwise direction and the crosswise direction, which define a position of said object on the screen, maybe calculated in said one frame and said another frame, respectively, and then, if the lowest digit in respective added values are not changed, said alternation may be carried out in said another frame, while said alternation may be postponed in said another frame if the lowest digit in respective added values are changed. Said one frame and said another frame may be continuous to each other.
According to still another aspect of the present invention, there is provided an image forming apparatus, comprising: a device for depicting a predetermined background; and a device for depicting an object, in which a transparent area and a non-transparent area are alternately arranged in at least one direction, so as to superpose said object on the background, wherein said device for depicting an object alternates said transparent area and said non-transparent area between a plurality of frames in at least part of said object.
In the image forming apparatus according to the present invention, said device for depicting an object may include: a device for detecting a change of a position of said object between one frame and another frame subsequent thereto; and a device for controlling alternation of said transparent area and said non-transparent area on the basis of said change.
Said device for controlling alternation may decide whether or not a predetermined area on a screen, which is identical with said transparent area in said one frame, is identical with said transparent area again in said another frame on an assumption that the alternation is not performed, and if identical, may carry out said alternation in said another frame while may postpone said alternation in said another frame if not identical.
Said transparent area and said non-transparent area may alternately be arranged by one pixel in a lengthwise direction and a crosswise direction, and said device for controlling alternation may calculate a binary value by adding coordinate values in the lengthwise direction and the crosswise direction, which define a position of said object on the screen, in said one frame and said another frame, respectively, and then, if the lowest digit in respective added values are not changed, may carry out said alternation in said another frame, while may postpone said alternation in said another frame if the lowest digit in respective added values are changed. Said one frame and said another frame may be continuous to each other.
A background in the present invention may be observed at the back of the object, in which transparent area and non-transparent area are arranged, according to the present invention. Further, other object, a texture and other various elements maybe treated as the background in the present invention. The present invention is not limited to a case such that all of the transparent areas and the non-transparent areas of the object are alternated but it includes a case such that the transparent areas and the non-transparent areas of the object are partially alternated. All of the transparent areas and the non-transparent areas may partially be alternated, respectively or the transparent areas and the non-transparent areas as a portion of the object may be alternated entirely or partially.